Cut back the foliage in early spring to within a few inches of the ground. In contrast to its ground-hugging relatives, Phlox paniculata , or garden phlox, is tall. Garden phlox is a colorful, long-lasting feature in sun-drenched summer gardens, which makes them a valuable asset in continuously blooming flower beds. Major tall phlox cultivars are 'David,' which has white flowers and large leaves that die back at the end of the growing season, and the cold-hardy 'Nora Leigh' with variegated leaves and pretty two-tone white and magenta blossoms. Hardy hibiscus, Hibiscus moscheutos , goes by common names such as "rose mallows" and "swamp mallows." But some gardeners prefer "hardy hibiscus" and "dinner-plate hibiscus," which are names befitting these cold-hardy plants that nevertheless bear large blooms reminiscent of the tropics.
The most common cultivars are 'Disco Belle Rosy Red' and 'Galaxy,' which bear blooms that are white, bi-colored, red, or pink. Popular hardy hibiscus cultivars grow up to 2.5 feet tall; in the case of 'Galaxy,' saucer-like blooms can span up to 10 inches across. While each bloom lives only a day or two, they are quickly replaced by newcomers. Hardy hibiscus plants should be grown in full sun and in average to wet soil. The orange flowers of butterfly weed, Asclepias tuberosa , carry out the work of the plant name: They attract monarch butterflies as well as tiger swallowtails and black swallowtails—both the caterpillar and the mature flyer—and even hummingbirds. Also known as Indian paintbrush, orange milkweed, pleurisy root, and yellow milkweed, butterfly weed blooms from early summer to the first frost in most areas. It grows up to 2 feet tall and has glossy leaves and seed pods. If you want to avoid an invasion of butterfly weed, cut off the seed pods before they open. Hardy butterfly weed is well-adapted to less-than-ideal conditions, growing well in clay soil and in dry or rocky soil.
It does best in full sun, but it tolerates some shade. Gaillardia , or blanket flower, is a short-lived, late-blooming perennial with richly colored, daisy-like flowers. There are more than two dozen species of Gaillardia, but most of the modern blanket flowers are Gaillardia x grandiflora, which was crossbred from two hardy Gaillardia species. Although short-lived, Gaillardia can reseed and sprawl through the garden. Since the original 12- to 18-inch-high plants are hybrids, expect some variation from self-seeding. Generally, the leaves are gray-green and lance-shaped, while the 3- to 5-inch-diameter flowers, some with petals surrounding disks and others with trumpet-shaped florets surrounding a disk, come in gorgeous shades of yellow and red. Blanket flowers love full sun, but they can handle partial shade, although they get a bit floppy and will not flower as profusely. Tall sedums such as 'Autumn Joy' are unparalleled garden performers that look good through all four seasons. There is no need to deadhead these plants, which thrive in well-drained soil and full sun. If the plants flop, they can be cut back in early summer to form a bushier, sturdier plant. Sedum can go years without division, but once the plant begins to thin out in the center, a division is necessary. These tough and adaptable plants tend to bloom in beautiful shades of pink and mauve for two to three months. The colors start out pale and deepen as they mature. Tall 'Showy Stonecrop' sedum doesn't bloom until the fall and requires little care. Their thick, succulent leaves are able to withstand drought and rainy weather. The flower buds form early and remain attractive well into winter. If the deer didn’t eat them, sedum would be a perfect plant. 'Border Stonecrop' is a small section of the hundreds of species of sedum. These taller sedums have thick stems, fleshy leaves, and tight flower heads. Tall sedum grows from 6 to 24 inches tall and can spread out up to 24 inches across. Although sedum flowers don't open until late summer or early fall, the flower heads form early in the season. They start off green like a broccoli bud, and slowly change color, usually from pink to mauve. Sedum grows best in full sun and is drought tolerant. They can also be grown in partial shade, but such plants will not be very sturdy.
Purple flowers, like blue blossoms, have a soothing emotional effect when used in the landscape. Bearing a color that has long been a symbol of royalty, purple flowers also suggest richness and elegance. Available in many shade variations, including violet and magenta, purple flowers are available in hundreds of varieties, from spring bulbs to fall-blooming wildflowers, from meek groundcovers to bold climbers. Here are 14 great options for including purple hues in your garden. A former Perennial Plant of the Year award winner (1997), May Night salvia produces small, bluish-purple blooms on flower spikes about 2 feet tall.
The sword-shaped leaves are more robust than those on 'Blue Hill' salvia. May Night salvia is known for a long blooming period (May through June), making it a valuable landscape plant. Like other salvias, this one is a great choice for perennial borders, cottage gardens, butterfly gardens or wild gardens. Salvia 'Caradonna' is similar to 'May Night,' but is a deeper shade of purple and with a more slender flower stalk that highlights the flowers.